Global Dirac optical potential from helium to lead

Abstract

We present a parametrization and two fits to proton nucleus scattering data from 20 to 1040 MeV and mass ranges from $^{4}\mathrm{He}$ to $^{208}\mathrm{Pb}$. We show that $^{4}\mathrm{He}$ can be included with the other nuclei instead of having to be treated separately as previously [B. C. Clark, E. D. Cooper, and S. Hama, Phys. Rev. C 73, 024608 (2006)]. An interesting change of sign in the imaginary potentials at low energies and high densities is noted. This may be an indicator of density dependence in the relativistic $g$ matrix.